This invention relates to a method for enhancing bioremediation of hydrocarbon contaminated soils. More particularly, a method of mixing cationic ion exchange resins with hydrocarbon contaminated soils to promote growth of organisms capable of degrading alkanes and other petroleum derived hydrocarbons is described.
Hydrocarbons such as crude petroleum and petroleum derived products can be characterized as a complex mixture of of straight and branched alkanes or alkenes, saturated ring compounds, and aromatic compounds. Small amounts of sulfur, nitrogen, or oxygen are also covalently attached to these various hydrocarbon chains. Gasoline, kerosene, burner fuel oil, diesel oil, gas turbine oil, and aviation fuel are examples of petroleum derived fuel oils, distillates, or catalytically processed petroleum fractions widely used by industry because of their relative low cost, stability and high heat value resulting from burning with oxygen. However, this widespread use has a concomitantly associated environmental cost related to contamination of soils resulting from spillage, seepage, or accidental release of petroleum derived hydrocarbons.
In the past, a generally accepted procedure for controlling possible environmental damage of hydrocarbon contaminated soil involved permanent removal of the contaminated soil to a secure landfill. However, given the decreasing availability of landfills willing to. accept hazardous wastes, the high cost of transport and removal of soil from a hydrocarbon contaminated sites, and the potential liability exposure associated with offsite transport and disposal, landfill disposal of hydrocarbon contaminated soil is becoming an increasingly unattractive means for handling hydrocarbon contaminated soils.
An alternative procedure for reducing the amount of hydrocarbon contamination of soils is known as bioremediation. Bioremediation relies on the hydrocarbon degrading abilities of biologic materials such as bacteria, saprophytes, bacterial enzymes, or saprophytic enzymes to degrade contaminated soils. The hydrocarbon degrading biologic materials are often naturally present in contaminated soils, and given sufficient time can naturally degrade the hydrocarbon contaminants. However, this natural degradation process can often be promoted by directly adding biologic materials to soil in an amount sufficient to degrade the hydrocarbons, or by encouraging the proliferation of hydrocarbon degrading organisms, either naturally present in soil or present as a result of inoculation. Proliferation of hydrocarbon degrading organisms can also be encouraged by the addition of nutrients to soil or by adjusting the soil conditions to favor growth of the desired organisms.
Bioremediation of hydrocarbon contaminated soils is favored over soil removal or chemical treatment of soil because of the lower cost, proven effectiveness, and ability for on site reduction of hydrocarbon contamination. However, these advantages can be outweighed by the substantial length of time necessary for bioremediation. Even under optimum conditions, months or years may be required to reduce the levels of hydrocarbon contamination of soils to a desired level. This disadvantage has greatly limited the potential use of bioremediation to reduce hydrocarbon contamination of soils.
It is therefore an object of this invention to reduce the levels of hydrocarbon contamination of soils by promoting the growth of organisms capable of degrading hydrocarbons contaminating the soil.
It is a further object of this invention to alter the chemical properties of hydrocarbon contaminated soil to promote the proliferation of bacteria and other organisms capable of degrading hydrocarbon contaminants.
Yet another object of this invention is to increase the acidity of soil to promote the proliferation of bacteria and other organisms capable of degrading hydrocarbon contaminants.
Still another object of this invention is to reduce the time required to degrade hydrocarbon contaminants to acceptable levels.
A further object of this invention is to provide a method for application of an inexpensive composition to hydrocarbon contaminated soil to promote cost effective onsite bioremediation.